A tuned mass damper (TMD) provides improved damping to structures and devices at a single frequency by tuning the damper""s natural frequency to be at or close to the single frequency. TMDs are attached to the structure at an effective position, usually the anti-node, to counteract the device""s vibration. The vibration stimulates the TMD to oscillator independently, 180 degrees out of phase, reducing the device""s vibration.
A TMD typically is adjusted at the factory by changing springs or removing material from the oscillating mass, estimating the frequency of the device to be damped. The typical TMD comprises a mass, a spring and a damping means which form a system with a specific natural resonant frequency and because of that structure it is difficult to tune that frequency.
A TMD according to invention is adjustable by utilizing an adjustment screw that is retracted or advanced, changing the number of active coils in a spring that engages a damping mass in a sealed TMD. The screw adjustment changes the spring rate and the natural frequency of the spring-mass combination but does not compress the spring.
Objects, benefits and features of the invention will be apparent to one of ordinary skill in the art from the drawing and following description.